Publication Date:
2017-04-19
Description:
〈span class="paragraphSection"〉〈div class="boxTitle"〉Abstract〈/div〉Electrical conductance 〈span style="font-style:italic;"〉G〈/span〉 at 100 kHz of Berea sandstone initially saturated with varying NaCl concentrations was measured by an impedance meter at decreasing water saturation. The obtained conductance 〈span style="font-style:italic;"〉G〈/span〉 values can be well simulated by the model equation composed of conductance of bulk pore water and that of mineral surfaces by introducing both tortuosities of bulk pore water τ〈sub〉b〈/sub〉 and mineral surfaces τ〈sub〉s〈/sub〉. The surface conductivity Σ〈sub〉s〈/sub〉 = 2.1 × 10〈sup〉− 10〈/sup〉 S and the tortuosity of mineral surfaces τ〈sub〉s〈/sub〉 = 2.6 in this equation can be valid for most of the data at varying water saturation except for the lowest water saturation (〈span style="font-style:italic;"〉S〈/span〉〈sub〉w〈/sub〉 = 0.05). The tortuosity of pore water τ〈sub〉b〈/sub〉 increased from 1.7 at 〈span style="font-style:italic;"〉S〈/span〉〈sub〉w〈/sub〉 = 1.0 to 15 at 〈span style="font-style:italic;"〉S〈/span〉〈sub〉w〈/sub〉 = 0.05 with a power law relationship. The present electrical conduction model with double tortuosities of bulk pore water τ〈sub〉b〈/sub〉 and mineral surfaces τ〈sub〉s〈/sub〉 can be considered as an alternative expression of the combined Archie's first and second laws in terms of tortuosities and would be useful for describing conductance of electrolyte containing partially saturated rocks including very low water saturation.〈/span〉
Print ISSN:
0956-540X
Electronic ISSN:
1365-246X
Topics:
Geosciences
Published by
Oxford University Press
on behalf of
The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
